Michael Franti didn’t bust a gut when, 20 years into his music career, he scored his first Top 20 radio hit with 2010’s exuberant “Say Hey (I Love You).” But the veteran singer, songwriter and leader of the genre-leaping band Spearhead did rupture his appendix — although the timing was purely coincidental.

“To me, having a song played on the radio is really exciting,” said Franti, who brings Spearhead to San Diego on Saturday to headline the third annual KPRI Block Party at Liberty Station. “But it’s funny to describe what a ‘hit’ record is. When I was in my first band, The Beatnigs, and we sold our first 1,000 records, I was so excited. I was like: ‘This is it! It’s the greatest thing in the world!’ ”

With “Say Hey,” the Bay Area-based Franti and Spearhead were introduced to a large new mainstream audience. That audience is far greater in size, if perhaps less musically discriminating, than the loyal cult following Spearhead had built through its seemingly nonstop touring.

“Tonight, we’re playing a venue in Vancouver I played in 10 years ago, as an opening act, and we’re headlining,” said Franti, whose engaging new album with Spearhead, “All People,” dropped in July. “But it took me 20 years of making music to have a song chart and an album get (radio) play. When it happened, I really appreciated it for what it was.

“When I was a kid, I’d listen to Top 40 radio with my dad on long car trips, and we’d all sing along. It became a part of my life and collective memory. When my songs are on the radio that way and enter people’s lives, it’s significant to me. But I never felt any pressure (after ‘Say Hey’), like: ‘Oh, you had a hit song, now the next one needs to be bigger and better.’ I just want to write the best song I can, go out on tour and do the best I can.”

Franti did experience a “Say Hey” backlash from some longtime fans, just as the Grateful Dead did when “Touch of Grey” gave that seminal Bay Area band its only radio hit in 1987.

“I have (experienced) that from time to time,” acknowledged Franti, who first earned national attention in the early 1990s as a member of the politically inspired Disposable Heroes of Hiphoprisy.

“Some people say: ‘I really liked the hard-core political stuff you did, then I heard you on the radio.’ It’s impossible to please everyone, but the artists I love are artists who were able to write songs about their own lives. That’s what makes John Lennon such a powerful artist to me. He wrote political songs about the world and beautiful love songs like ‘Woman.’ Bob Marley was another one. So was Johnny Cash, Bob Dylan, Marvin Gaye … .”

At 47, Franti feels he is coming into his own as a musician. His understanding of his craft has grown. So has his appreciation for how music can resonate with listeners in subtle as well as overt ways.

"You know, when I first started out I don’t feel like I had the same understanding I have now about the power of emotion (in music)," he said. "I love artists like (proto-rappers) The Last Poets and Gil Scott Heron, who were real poets, almost literary people, where the words were the most important thing.

"What Ive grown into, I think, after having more experience is that the feeling you get is the most important thing, Like, last night, we did a studio session, a sort of remix, and we had our drummer in there. And the engineer was asking: 'What do you think of the kick drum, and how does the snare sound?' Which I'm interested in. But I have to hear the whole thing at once, rather than dissecting how a cymbal sounds, which loses a lot of the power and mystery of music. That's where I've really grown, not just (in crafting) certain phrases or words, but in how this whole thing hits your heart."